An adtech identifier is a device or browser signal that advertising systems use to recognize, group, or target users. Examples include mobile advertising IDs, browser cookies, and signals derived from an IP address. These identifiers can help select ads across apps and websites, but they do not necessarily reveal a person’s real-world identity on their own.
In cybersecurity, identifiers matter because they can help an operator narrow ad delivery to particular devices or audiences. If advertising infrastructure is misused, targeting signals may become part of a surveillance or spyware-delivery pipeline, including a zero-click path in which content is rendered without a user clicking a link. Defenses include limiting unnecessary tracking, restricting ad exposure in high-risk environments, keeping devices patched, and monitoring for suspicious behavior. An identifier can enable targeting; it does not by itself prove a device was infected.